@import 'https://use.fontawesome.com/releases/v5.5.0/css/all.css';
body {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  background: url(./img/bg1.jpg);
  background-size: cover;
  animation: slide 20s infinite;
}

.login-box {
  width: 280px;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
}
.login-box h1 {
  float: left;
  font-size: 40px;
  border-bottom: 6px solid #4caf50;
  margin-bottom: 20px;
  padding: 13px 0;
}

.alert-box {
  height: 28px;
  line-height: 28px;
  float: left;
  width: 100%;
  margin-bottom: 10px;
  border: 2px solid #dfe4ea;
  border-radius: 8px;
  text-align: center;
  visibility: hidden;
}

.success {
  background: rgba(123, 237, 159, 0.75);
}

.danger {
  background: rgba(255, 71, 87, 0.75);
}

.textbox {
  width: 100%;
  overflow: hidden;
  font-size: 20px;
  padding: 8px 0;
  margin: 8px 0;
  border-bottom: 1px solid #4caf50;
}
.textbox i {
  width: 26px;
  float: left;
  text-align: center;
}
.textbox input {
  border: none;
  outline: none;
  background: none;
  color: white;
  font-size: 18px;
  width: 80%;
  float: left;
  margin: 0 10px;
}

.btn {
  width: 100%;
  background: none;
  border: 2px solid #4caf50;
  color: white;
  padding: 5px;
  font-size: 18px;
  cursor: pointer;
  margin: 12px 0;
}

.btn:hover,
.textbox:hover {
  transform: scale(1.1);
}

.tips {
  color: white;
  text-decoration: none;
}

.tips:hover {
  display: inline-block;
  transform: scale(1.2);
}

@keyframes slide {
  25% {
    background: url(./img/bg2.jpg);
    background-size: cover;
  }
  50% {
    background: url(./img/bg3.jpg);
    background-size: cover;
  }
  75% {
    background: url(./img/bg4.jpg);
    background-size: cover;
  }
  100% {
    background: url(./img/bg1.jpg);
    background-size: cover;
  }
}
